Step 1: Recalling the Text:
The peddler's transformation is central to the story — Edla's compassion changes his self-image and actions.
Step 2: Content of the Letter:
The letter expressed gratitude for being addressed and treated as 'Captain', not a criminal; he returned the stolen thirty kronor and gifted her the iron rattrap as a keepsake, in recognition of her rare kindness toward him.
Final Answer:
In the letter, the peddler thanked Edla for her dignity and kindness towards him, returned the money he had stolen, and gave her the rattrap as a Christmas gift, honouring the identity of 'Captain von Ståhle' she had given him.